This invention relates generally to devices for interventional therapeutic treatment or vascular surgery for treatment of defects in the vasculature, and more particularly concerns a system and method for delivering a self-expanding stent through a catheter to a treatment site in a vasculature of a patient, such as for treatment of aneurysms.
A basic approach to delivery of a self-expanding stent in a patient's vasculature typically involves advancing the stent through a sleeve or microcatheter by pushing the stent distally through the sleeve or microcatheter until the stent emerges from a distal end of the sleeve or microcatheter at a desired location in the patient's vasculature. At that point, the self-expanding stent is unrestrained, and ideally the self-expanding stent deploys at the desired location in the patient's vasculature. However, this basic approach is typically a “push only” system, due to the self-expanding nature of the stent, since once the stent is deployed, the position of the stent can no longer be manipulated forwards or backwards, so that retraction of the stent is typically not possible once the self-expanding stent has been deployed.
In one type of delivery system, a self-expanding stent is radially compressed between two pushing surfaces, one proximal and one distal to the stent, so that as long as the entire self-expanding stent remains inside a sleeve or microcatheter, the self-expanding stent can be advanced and retracted. However, if any portion of the distal end of the stent is revealed outside of the microcatheter, the ability to retract the self-expanding stent is lost, and at that point the delivery system acts essentially the same as a “push only” system. Another type of delivery system is known that utilizes a physical feature on a self-expanding stent to capture a proximal portion. Such a proximal capture type of delivery system allows advancement and retraction, even after a distal portion of the stent has exited a sleeve or microcatheter. However, this type of delivery system requires a certain feature to be included in the stent design, which is not always feasible.
It would be desirable for a system for delivering a self-expanding stent to allow control of both advancement and retraction of the stent, which requires that the delivery system have some type of capture interface with the stent, such as by providing an arrangement on the delivery system allowing capture of all or a portion of the stent, or capture of a particular interfacing feature on the stent. It would be desirable to provide such a capture interface at a proximal end of the stent, so that a distal portion of the stent can be revealed and allowed to deploy to a partial or fully expanded diameter prior to releasing the entire stent from the delivery system, to allow retraction and repositioning of the self-expanding stent before the entire stent is released from the delivery system. It would be desirable to provide such a capture interface as a “positive capture” delivery system for delivering a self-expanding stent, in which the self-expanding stent is held proximally by the delivery system regardless of whether the self-expanding stent is positioned within or wholly outside of a delivery sleeve or microcatheter, so that the entire stent can be advanced out of the distal end of the microcatheter without releasing the stent, and can be subsequently retracted fully back into the delivery sleeve or microcatheter. With such a “positive capture” delivery system it also would be desirable that a separate, deployment action be required in order to release the self-expanding stent, in order to provide the delivery system with a maximal versatility. The present invention meets these and other needs.